Percutaneous registration apparatus and method for use in computer-assisted surgical navigation

ABSTRACT

An apparatus and procedures for percutaneous placement of surgical implants and instruments such as, for example, screws, rods, wires and plates into various body parts using image guided surgery. An apparatus for use with a surgical navigation system, an attaching device rigidly connected to a body part, such as the spinous process of a vertebrae, with an identification superstructure rigidly but removably connected to the attaching device. This identification superstructure, for example, is a reference arc and fiducial array which accomplishes the function of identifying the location of the superstructure, and, therefore, the body part to which it is fixed, during imaging by CAT scan or MRI, and later during medical procedures.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/423,332 filed on Apr. 24, 2003; which is a reissue of 09/148,498filed Sep. 4, 1998 which is now U.S. Pat. No. 6,226,548 issued on May 1,2001; which claims rights under 35 U.S.C. §119 on provisionalapplication No. 60/059,915, filed on Sep. 24, 1997. The disclosures ofthe above applications are incorporated herein by reference.

FIELD

The present teachings relate generally to guiding, directing, ornavigating instruments or implants in a body percutaneously, inconjunction with systems that use and generate images during medical andsurgical procedures, which images assist in executing the procedures andindicate the relative position of various body parts, surgical implants,and instruments. In particular the teachings relate to apparatus andminimally invasive procedures for navigating instruments and providingsurgical implants percutaneously in the spine, for example, to stabilizethe spine, correct deformity, or enhance fusion in conjunction with asurgical navigation system for generating images during medical andsurgical procedures.

BACKGROUND

Typically, spinal surgical procedures used, for example, to providestabilization, fusion, or to correct deformities, require largeincisions and substantial exposure of the spinal areas to permit theplacement of surgical implants such as, for example, various forms ofscrews or hooks linked by rods, wires, or plates into portions of thespine. This standard procedure is invasive and can result in trauma,blood loss, and post operative pain. Alternatively, fluoroscopes havebeen used to assist in placing screws beneath the skin. In thisalternative procedure at least four incisions must be made in thepatient's back for inserting rods or wires through previously insertedscrews. However, this technique can be difficult in that fluoroscopesonly provide two-dimensional images and require the surgeon to rotatethe fluoroscope frequently in order to get a mental image of the anatomyin three dimensions. Fluoroscopes also generate radiation to which thepatient and surgical staff may become over exposed over time.Additionally, the subcutaneous implants required for this procedure mayirritate the patient. A lever arm effect can also occur with the screwsthat are not connected by the rods or wires at the spine. Fluoroscopicscrew placement techniques have traditionally used rods or plates thatare subcutaneous to connect screws from vertebra to vertebra. This isdue in part to the fact that there is no fluoroscopic technique that hasbeen designed which can always adequately place rods or plates at thesubmuscular region (or adjacent to the vertebrae). These subcutaneousrods or plates may not be well tolerated by the patient. They also maynot provide the optimal mechanical support to the spine because themoment arm of the construct can be increased, thereby translating higherloads and stresses through the construct.

A number of different types of surgical navigation systems have beendescribed that include indications of the positions of medicalinstruments and patient anatomy used in medical or surgical procedures.For example, U.S. Pat. No. 5,383,454 to Bucholz; PCT Application No.PCT/US94/04530 (Publication No. WO 94/24933) to Bucholz; and PCTApplication No. PCT/US95/12894 (Publication No. WO 96/11624) to Bucholzet al., the entire disclosures of which are incorporated herein byreference, disclose systems for use during a medical or surgicalprocedure using scans generated by a scanner prior to the procedure.Surgical navigation systems typically include tracking means such as,for example, an LED array on the body part, LED emitters on the medicalinstruments, a digitizer to track the positions of the body part and theinstruments, and a display for the position of an instrument used in amedical procedure relative to an image of a body part.

Bucholz et al. WO 96/11624 is of particular interest, in that itidentifies special issues associated with surgical navigation in thespine, where there are multiple vertebral bodies that can move withrespect to each other. Bucholz et al. describes a procedure foroperating on the spine during an open process where, after imaging, thespinous process reference points may move with respect to each other. Italso discloses a procedure for modifying and repositioning the imagedata set to match the actual position of the anatomical elements. Whenthere is an opportunity for anatomical movement, such movement degradesthe fidelity of the pre-procedural images in depicting theintra-procedural anatomy. Therefore, additional innovations aredesirable to bring image guidance to the parts of the body experiencinganatomical movement.

Furthermore, spinal surgical procedures are typically highly invasive.There is, thus, a need for more minimally invasive techniques forperforming these spinal procedures, such as biopsy, spinal fixation,endoscopy, spinal implant insertion, fusion, and insertion of drugdelivery systems, by reducing incision size and amount. One such way isto use surgical navigation equipment to perform procedurespercutaneously, that is beneath the skin. To do so by means of surgicalnavigation also requires apparatus that can indicate the position of thespinal elements, such as, for example the vertebrae, involved in theprocedure relative to the instruments and implants being insertedbeneath the patient's skin and into the patient's spine. Additionally,because the spinal elements naturally move relative to each other, theuser requires the ability to reorient these spinal elements to alignwith earlier scanned images stored in the surgical navigation systemcomputer, to assure the correct location of those elements relative tothe instruments and implants being applied or inserted percutaneously.

In light of the foregoing, there is a need in the art for apparatus andminimally invasive procedures for percutaneous placement of surgicalimplants and instruments in the spine, reducing the size and amount ofincisions and utilizing surgical navigation techniques.

SUMMARY

Accordingly, the present teachings are directed to apparatus andprocedures for percutaneous placement of surgical implants andinstruments such as, for example, screws, rods, wires and plates intovarious body parts using image guided surgery. Various embodiments aredirected to apparatus and procedures for the percutaneous placement ofsurgical implants and instruments into various elements of the spineusing image guided surgery.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, anapparatus for use with a surgical navigation system and comprises anattaching device rigidly connected to a body part, such as the spinousprocess of a vertebrae, with an identification superstructure rigidlybut removably connected to the attaching device. This identificationsuperstructure is a reference arc and fiducial array, which accomplishesthe function of identifying the location of the superstructure, and,therefore, the body part to which it is fixed, during imaging by CATscan or MRI, and later during medical procedures.

According to various embodiments, the attaching device is a clamp withjaws and sharp teeth for biting into the spinous process.

According to various embodiments, the fixture is a screw, having a head,wherein the screw is implanted into the spinous process and a relativelyrigid wire is attached to the head of the screw and also implanted intothe spinous process at an angle to the axis of the screw to prevent thescrew from rotating in either direction.

According to various embodiments, the superstructure includes a centralpost, and a fiducial array and a reference arc rigidly but removablyattached to the central post. The fiducial array is composed ofimage-compatible materials, and includes fiducials for providing areference point, indicating the position of the array, which are rigidlyattached to the fiducial array, composed of, for example titanium oraluminum spheres. The reference arc includes emitters, such as, forexample Light Emitting Diodes (“LEDs”), passive reflective spheres, orother tracking means such as acoustic, magnetic, electromagnetic,radiologic, or micropulsed radar, for indicating the location of thereference arc and, thus, the body part it is attached to, during medicalprocedures.

According to various embodiments, a method for monitoring the locationof an instrument, surgical implants and the various portions of thebody, for example, vertebrae, to be operated on in a surgical navigationsystem comprising the steps of: attaching a fixture to the spinousprocess; attaching a superstructure including a fiducial array withfiducials and a reference arc to the fixture; scanning the patient usingCT, MRI or some other three-dimensional method, with fiducial arrayrigidly fixed to patient to identify it on the scanned image; andthereafter, in an operating room, using image-guided technology,touching an image-guided surgical pointer or other instrument to one ormore of the fiducials on the fiducial array to register the location ofthe spinal element fixed to the array and emitting an audio, visual,radiologic, magnetic or other detectable signal from the reference arcto an instrument such as, for example, a digitizer or otherposition-sensing unit, to indicate changes in position of the spinalelement during a surgical procedure, and performing a surgical ormedical procedure percutaneously on the patient using instruments andimplants locatable relative to spinal elements in a known position inthe surgical navigation system.

In another aspect, the method includes inserting screws or rigid wiresin spinal elements in the area involved in the anticipated surgicalprocedure before scanning the patient, and after scanning the patientand bringing the patient to the operating area, touching an image-guidedor tracked surgical pointer to these screws and wires attached to thevertebrae to positively register their location in the surgicalnavigation computer, and manipulating either the patient's spine or theimage to align the actual position of the spinal elements with thescanned image.

In another aspect, the method includes percutaneously implanting screwsinto spinal elements, which screws are located using image guidedsurgical navigation techniques, and further manipulating the orientationof the screw heads percutaneously using a head-positioning probecontaining an emitter, that can communicate to the surgical navigationcomputer the orientation of the screw heads and position them, by use ofa specially designed head-positioning tool with an end portion thatmates with the heads of the screws and can rotate those screw heads toreceive a rod, wire, plate, or other connecting implant. If a rod isbeing inserted into the screw heads for example, the method furtherincludes tracking the location and position of the rod, percutaneouslyusing a rod inserter having one or more emitters communicating thelocation and orientation of the rod to the surgical navigation computer.

According to various embodiments, a system and method is provided to auser, such as a surgeon, to track an instrument and surgical implantsused in conjunction with a surgical navigation system in such a mannerto operate percutaneously on a patient's body parts, such as spinalvertebrae which can move relative to each other.

According to various embodiments, is provided a system and method tosimply and yet positively indicate to the user a change in position ofbody parts, such as spinal vertebrae segments, from that identified in astored image scan, such as from an MRI or CAT scan, and provide a methodto realign those body parts to correspond with a previously stored imageor the image to correspond with the actual current position of the bodyparts.

According to various embodiments, is provided a system or method forallowing a fiducial array or reference arc that is removable from alocation rigidly fixed to a body part and replaceable back in thatprecise location.

According to various embodiments, is provided a system and method forpositively generating a display of instruments and surgical implants,such as, for example screws and rods, placed percutaneously in a patientusing image-guided surgical methods and techniques.

According to various embodiments, is provided a percutaneous referencearray and fiducial array, as described herein, to be used to registerand track the position of the vertebrae for the purposes of targeting aradiation dose to a diseased portion of said vertebrae using atraditional radiosurgical technique.

Additional application of the teachings will be set forth in part in thedescription which follows, and in part will be obvious from thedescription, or may be learned by practice of the teaching. Theapplications of the teachings will be realized and attained by means ofthe elements and combinations particularly pointed out in thisdescription.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive.

Further areas of applicability of the present teachings will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and various examples, whileindicating various embodiments, are intended for purposes ofillustration only and are not intended to limit the scope of theteachings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate various embodiments of theteachings and together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a schematic diagram of various embodiments of a superstructurefor use with the current teachings, including a reference arc, centerpost and fiducial array and rigid Kirschner wires (“K wires”) and screwsplaced in the spine for use with a surgical navigation system forpercutaneous spinal surgical procedures.

FIG. 1A is an enlarged view of the superstructure depicted in FIG. 1engaging a vertebra by a clamp and also K wires implanted in adjacentvertebrae in the superior and inferior positions of the spinous process.

FIG. 2 is a diagram of various embodiments of a clamp fixture for rigidconnection to the spinous process of a single vertebrae with an H-shapedfiducial array attached to a center post rigidly attached to the clampand a mating connector at the tip of the post for mating with areference array, and a reference array for use in the current invention.

FIG. 2A is a side view of FIG. 2.

FIG. 2B is another side view of FIG. 2.

FIG. 2C is a top view of FIG. 2.

FIG. 2D is an exploded view of FIG. 2 without the reference arc.

FIG. 2E is an exploded view of the interface of the center post andclamp of FIG. 2.

FIG. 3 is a diagram of a W-Shaped fiducial array mounted to a centralpost with generally spherical fiducials attached to the array, formounting to a single vertebrae.

FIG. 3A is a side view of FIG. 3.

FIG. 3B is another side view of FIG. 3.

FIG. 3C is a top view of FIG. 3.

FIG. 4 is a diagram of a reference arc and fiducial attached to a centerpost for use in the current invention in mounting to a single vertebrae.

FIG. 4A is a side view of FIG. 4.

FIG. 4B is a back view of FIG. 4.

FIG. 4C is a top view of FIG. 4.

FIG. 4D is an expanded view of FIG. 4.

FIG. 4E is an expanded side view of FIG. 4.

FIG. 4F is an expanded view of the array foot and shoe of FIG. 4E.

FIG. 5 is a diagram according to various embodiments of a fixture usinga cannulated screw for insertion into a vertebrae, with Kirschner wiremounted on a central post and including a fiduciary array and referencearc combined on a single structure.

FIG. 6 is a side view of the screw and Kirschner wire fixture of FIG. 5implanted in a spinous process of a vertebrae.

FIG. 7 is a diagram of a screw-head positioning probe and multiaxialscrew for insertion into a single vertebrae.

FIG. 7A is a diagram of the screw of FIG. 7.

FIG. 8 is a diagram of a head positioning probe, multiaxial screw andspinal segment.

FIG. 9 is a diagram of a rod inserter with an LED.

FIG. 10 is a diagram of various embodiments of the teachings including acannulated tube and attachment for holding a reference arc.

FIG. 11 is a diagram of the cannulated tube of FIG. 10 with a referencearc and screw for attachment to a spinal process.

FIG. 12 is a posterior view of spinal segment and implanted screwsbefore alignment.

FIG. 13 is a posterior view of spinal segment and implanted screws afteralignment.

DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS

Reference will now be made in detail to various embodiments, an exampleof which is illustrated in the accompanying drawings. Wherever possible,the same reference numbers will be used throughout the drawings to referto the same or like parts. The following example is intended to bepurely exemplary.

As generally described in PCT/US95/12894, the entire disclosure of whichis incorporated herein by reference, a typical surgical navigationsystem is shown in FIG. 1. A computer assisted image-guided surgerysystem, indicated generally at 10, generates an image for display on amonitor 106 representing the position of one or more body elements, suchas spinal elements fixedly held in a stabilizing frame or device such asa spinal surgery frame 125 commonly used for spinal surgery. A referencearc 120 bearing tracking means or emitters, such as for example LEDemitters 122, is mounted to the spinous process by a central post 150.The structures 20 and K wires 260 of FIG. 1 are depicted in more detailin FIG. 1A. The image 105 is generated from an image data set, usuallygenerated preoperatively by a CAT scanner or by MRI for example, whichimage 105 has reference points for at least one body element, such as aspinal element or vertebrae. The reference points of the particular bodyelement have a fixed spatial relation to the particular body element.

The system includes an apparatus such as a digitizer or other PositionSensing Unit (PSU), such as for example sensor array 110 on support 112for identifying, during the procedure, the relative position of each ofthe reference points to be displayed by tracking the position ofemitters 122 on arc 120. The system also includes a processor 114 suchas a PC or other suitable workstation processor associated withcontroller 108 for modifying the image data set according to theidentified relative position of each of the reference points during theprocedure, as identified by digitizer 110. The processor 114 can then,for example, generate an image data set representing the position of thebody elements during the procedure for display on monitor 106. Asurgical instrument 130, such as a probe or drill or other tool, may beincluded in the system, which is positioned relative to a body part andsimilarly tracked by sensor array 110.

In summary, the general operation of a surgical navigating system iswell known in the art and need not further be described here.

With further reference to FIGS. 1 through 6, a registration device 20 isrigidly fixed to a spinal element by, for example, a device such as abone clamp 30 depicted in FIG. 2. Alternatively, a screw retentiondevice 40, such as the cannulated screw 42 depicted in FIG. 5, anddescribed in more detail below, can be used.

With reference now to FIG. 2, bone clamp 30 is fixedly attached to thespinous process. The clamp 30 includes at least two blades (or jaws) 32with tips or teeth 34, which are preferably sharp, for driving togetherand penetrating soft tissue or more dense bone for rigid fixation to thespinous process. The teeth 34 are also preferably sized to accommodatethe bulb shape of the spinous process. The driving mechanism 40 is, forexample, a screw driven into a sleeve 41 and is also preferably locatedsuch that it will be accessible in a percutaneous manner. Attached tothe clamp 30 is a superstructure 20. The superstructure 20 includes acentral post 150 which is relocatable, that is, it fixes to the clamp 30in a rigid fashion, for example, as depicted in FIGS. 2D and 2E, bybeing inserted into a V-shaped wedge 44 orienting the post 150 front toback and providing a mating hole 48 along the wedge 44 for insertion ofpost 150 in a single orientation and also providing fasteners such asscrew 43 for tightening to lock the post 150 in place. The post 150 canbe removed and reapplied by loosening and tightening screw 43, such thatthe original geometry and orientation is maintained. The central post150 has at its apex a connector 60 with unique geometricalconfiguration, such as, for example, a starburst, onto which a spinalreference arc 120 of the superstructure 20 attaches. Any such standardreference arc 120 can be used, such as depicted in FIGS. 1A, 4, and 11,preferably including emitters 122, such as for example LEDs orreflective spheres for providing a positive indication of movement tothe surgical navigation system during a procedure.

Also rigidly attached to the central post 150, as part of thesuperstructure 20 preferably at a location closer to the skin, orpossibly collocated with or also performing the function of thereference arc 120, is a fiducial array 170, which can be of variousdifferent shapes, such as, for example the H-shaped frame 170 depictedin FIG. 2, the W-shaped frame 170′ as depicted in FIG. 3, the U-shapedframe 170″ as depicted in FIG. 4 or the X-shaped frame 120′, 170′″depicted in FIG. 5 (depicting a structure that is both a fiducial arrayand a reference arc). As depicted in FIGS. 2 and 3, this array caninclude fiducial points 29 or spheres 17, rigidly attached to fiducialarray 170, 170′ and is, for example, as depicted in FIG. 3,substantially in the shape of spheres 17 and of a material detectable bythe CAT scan or MRI, preferably titanium or aluminum. This fiducialarray such as 170 indicates to the surgical navigation system thelocation of the bone structure to which the clamp 30 and central post150 are attached by touching a pointed surgical tracker to fiducialpoints 29 or a cup-shaped probe to fiducial spheres 17, therebyindicating the center of the fiducial to the surgical navigationcontroller 114. The array 170 and central post 150 are also attached tothe clamp 30, as described above, in such a way that they can be removedand replaced in the same geometric orientation and location, forexample, by means of a uniquely shaped interface, for example, atriangle, or a single unique shape or a combination of unique angles orpins with the clamp 30 such that the post 150 can only be reinserted thesame way it was removed.

Additionally, the fiducial array 170, can be located at various heightson the post 150 to accommodate variations in patient tissue depth andsize, preferably as close to the patient's body as possible, and thenfixed at that specific height by the use of pins or indents matched toholes 19 (shown in FIG. 2) in the central post 150 or by placing therods 39 of H-shaped array 170 in different holes 31. The fiducial array170 also has, for example, divots 29 (shown in FIG. 2) shaped tointerface with an instrument such as a surgical pointer 130 which cantouch that divot 29 to register the location of the divot 29 and, thus,the location of the fiducial array 170 and likewise the spinal elementin the surgical navigation system. Multiple divots can be registered tofurther increase accuracy of the registration system. In one preferredembodiment of the array, the fiducials 17 or 29 can be mounted in amanner such that they can be adjusted, for example by mounting them on arotatable or collapsible arm 66 (as depicted in FIG. 3) that pivots andfolds together, to get the maximum distance between fiducials while notdramatically increasing the field of view required at the time ofscanning.

Alternatively, rather than using clamp 30, a screw 42 and rigid wire 45attachment, as depicted in FIGS. 5 and 6, may be used to rigidly attachthe central post of the superstructure 20 to a body element, such as,for example, a vertebrae. As depicted in FIG. 6, screw 42 is screwedinto the spinal process of spinal element 100. A rigid wire 45, post, orother sufficiently rigid fastener such as for example a Kirschner wire(K-wire), is inserted through the cannulation in the center of post 150and the screw 42 or is otherwise fixed to the screw 42, and exits thetip of the screw 42 at some angle, and is also implanted into the spinalelement 100 to prevent the screw 42 from rotating in either direction.

Another embodiment for preventing the superstructure 20 from rotating asdepicted in FIGS. 10 and 11 includes the insertion of a screw 85 througha cannulated tube 86 which has teeth 89 in the end (or V-shaped end)that would bite into the tip of the spinous process, preventingrotation.

Having described various embodiments of this apparatus of the presentsystem, a method of using this apparatus for registering a singlevertebrae will now be discussed. The operation of a surgical navigatingsystem is generally well known and is described in PCT/US95/12894.According to various embodiments method of operation, clamp 30 of FIG. 2or screw 42 and K-Wire 45 of FIG. 5 are implanted percutaneously througha small incision in the skin and rigidly attached to the spinal process.This attachment occurs with the clamp 30, by driving the blades 32 ofthe clamp 30 together to hold the spinous process rigidly. The centralpost 150 is then rigidly fixed to the clamp 30 or screw 42 and thefiducial array 170 is rigidly fixed to the central post 150. The patientis then scanned and imaged with a CAT scan or MRI with a field of viewsufficiently large to display the spinal anatomy and the clamp 30 orscrew 42 and the fiducial array 170. This scan is loaded into thesurgical navigation system processor 104.

After scanning the patient, the array 120 and post 150 can be removedfrom the patient, while leaving in place the rigidly connected clamp 30or screw 42. For example, as depicted in FIGS. 4D and 4E, a foot 55located below array 170″ engages with shoe 56 and rigidly connected byscrews 57 and 58. Before the surgical procedure, the post 150, array 120and other remaining portions of the superstructure 20, once removed, maybe sterilized. The patient is then moved to the operating room orsimilar facility from, for example, the scanning room.

Once in the operating room, the patient may be positioned in anapparatus, such as, for example, a spinal surgery frame 125 to help keepthe spinal elements in a particular position and relatively motionless.The superstructure 20 is then replaced on the clamp 30 or screw 42 in aprecise manner to the same relative position to the spinal elements asit was in the earlier CAT scan or MRI imaging. The reference arc 120 isfixed to the starburst or other interface connector 60 on the centralpost 150 which is fixed to the clamp 30 or screw 42. The operator, forexample a surgeon, then touches an instrument with a tracking emittersuch as a surgical pointer 130 with emitters 195 to the divots 29 on thefiducial array 170 to register the location of the array 170 and, thus,because the spinal process is fixed to the fiducial array 170, thelocation of the spinal element is also registered in the surgicalnavigation system.

Once the superstructure 20 is placed back on the patient, any instrument130 fitted with tracking emitters thereon such as, for example, a drillor screw driver, can be tracked in space relative to the spine in thesurgical navigation system without further surgical exposure of thespine. The position of the instrument 130 is determined by the userstepping on a foot pedal 116 to begin tracking the emitter array 190.The emitters 195 generate infrared signals to be picked up by cameradigitizer array 110 and triangulated to determine the position of theinstrument 130. Additionally, other methods may be employed to trackreference arcs, pointer probes, and other tracked instruments, such aswith reflective spheres, or sound or magnetic emitters, instead ofLED's. For example, reflective spheres can reflect infrared light thatis emitted from the camera array 110 back to the camera array 110. Therelative position of the body part, such as the spinal process isdetermined in a similar manner, through the use of similar emitters 122mounted on the reference frame 120 in mechanical communication with thespinal segment. As is well known in this art and described generally inPCT/US95/12894, based upon the relative position of the spinal segmentand the instrument 130 (such as by touching a known reference point) thecomputer would illustrate a preoperative scan—such as the proper CATscan slice—on the screen of monitor 106 which would indicate theposition of the tool 130 and the spinal segment for the area of thespine involved in the medical procedure.

For better access by the operator of various areas near the central post150, the fiducial array 170 can be removed from the central post 150,by, for example, loosening screw 42 and sliding the array 170 off post150, leaving the reference arc 120 in place or replacing it afterremoval of array 170. By leaving the reference arc 120 in place, theregistration of the location of the spinal process is maintained.Additionally, the central post 150, reference arc 120, and fiducialarray 170 can be removed after the spinal element has been registeredleaving only the clamp 30 or screw 42 in place. The entire surgicalfield can then be sterilized and a sterile post 150 and reference arc170 fixed to the clamp 30 or screw 42 with the registration maintained.

This surgical navigation system, with spinal element registrationmaintained, can then be used, for example, to place necessary anddesired screws, rods, hooks, plates, wires, and other surgicalinstruments and implants percutaneously, using image-guided technology.Once the location of the spinal element 100 involved in the procedure isregistered, by the process described above, in relation to the imagedata set and image 105 projected on monitor 106, other instruments 130and surgical implants can be placed under the patient's skin atlocations indicated by the instrument 130 relative to the spinal element100.

Additionally, the location of other spinal elements, relative to thespinal element 100 containing the fiducial array 170, can be registeredin the surgical navigation system by, for example, inserting additionalscrews 250, rigid wires 260, or other rigid implants or imageabledevices into the spinal segment.

For example, as depicted in FIG. 1, and in more detail FIG. 1A,additional screws 250 or rigid and pointed wires 260 are placed in thevertebrae adjacent to the vertebrae containing the clamp 30 and post 150prior to scanning. On the image 105 provided by monitor 106, the surgeoncan see the clamp 30 or screw 42 and fiducial array 170 and also theadditional screws 250, wires 260 or other imageable devices. When screws250 or other devices are used, these screws 250 (as depicted in FIG. 7)may contain a divot 256 or other specially shaped interface on the head255 so that a pointer probe 130 can be used to point to the head 255 ofthe screw 250 (or wire) and indicate the orientation of the screw 250 orwire 260 to the surgical navigation system by communicating to thecontroller 114 or by emission from LEDs 195 on probe 130 to digitizer110. The image of these additional screws 250 also appear in the scan.Once the patient is then moved to the operating facility, rather thanthe scanning area, the image of the screw 250 can be compared to theactual position of the screw 250 as indicated by the pointer probe 130that is touched to the head 255 of the screw 250 or wire 260. Ifnecessary, the operator can manipulate the position of the patient tomove the spinal element and thus the location of the screw 250 or wire260 to realign the spinal elements with the earlier image of the spine.Alternatively, the operator can manipulate the image to correspond tothe current position of the spinal segments.

For additional positioning information, the operator can placeadditional rigid wires 260 or screws 250 into the vertebrae, forexample, located at the superior (toward the patient's head) andinferior (towards the patient's feet) ends of the spinal process to moreaccurately position those vertebrae relative to the other vertebrae andthe image data. Additionally, the wires 260 and screws 250 implanted toprovide positioning information can also be equipped with emitters, suchas, for example, LEDs, to provide additional information to the surgicalnavigation system on the location of the wire 260 or screw 250, and thusthe vertebra to which they are affixed.

Alternatively, the patient can be placed in a position stabilizingdevice, such as a spinal surgery frame 125 or board, before a scan istaken, and then moved to the operating facility for the procedure,maintaining the spine segments in the same position from the time ofscanning until the time of surgery. Alternatively, a fluoroscope can beused to reposition the spinal segments relative to the earlier imagefrom the scan. An ultrasound probe can be used to take real-time imagesof the spinal segment which can be portrayed by monitor 106 overlayed orsuperimposed on image 105. Then the operator can manually manipulate thespinal elements and take additional images of these elements with thefluoroscope to, in an iterative fashion, align the spinal elements withthe previously scanned image 105.

Alternatively, a clamp 30 or screw 42 and superstructure 20 can berigidly fixed to each vertebra involved in the surgical or medicalprocedure to register the position of each vertebra as explainedpreviously for a single vertebra.

After the spinal elements are registered in the spine, various medicaland surgical procedures can be performed on that patient. For example,spinal implants, endoscopes, or biopsy probes can be passed into thespine and procedures such as, for example, spinal fusion, manipulation,or disc removal can be performed percutaneously and facilitated by thesurgical navigation image-guiding system. Additionally, a radiation dosecan be targeted to a specific region of the vertebrae.

One such procedure facilitated by the apparatus and methods describedabove is the percutaneous insertion of screws and rods, fixed todifferent vertebra in a spine to stabilize them. Once screws, forexample multiaxial screws 250, (as depicted in FIG. 12, beforemanipulation) are implanted through small incisions they can bemanipulated by a head-positioning probe 280. The final position ofscrews 250 and heads 255 are depicted in FIG. 13. This probe 280, asdepicted in FIG. 7, includes a head 285 that mates in a geometricallyunique fashion with the head 255 of the screw 250. An emitter, such as,for example, an LED array 380 on the probe 280, indicates the locationand orientation of the screw head 255 to the computer 114 of thesurgical navigation system by providing an optical signal received bydigitizer 110. The screw head 255 can then be rotatably manipulatedunder the patient's skin by the head positioning probe 280 to beproperly oriented for the receipt of a rod 360 inserted through therotating head 255. The operator can then plan a path from the head 255of each screw 250 to the other screws 250 to be connected. Then, withreference now to FIG. 9, an optically tracked rod inserter 245 alsoequipped with emitters, such as, for example LEDs 247, can be placedthrough another small incision to mate with and guide a rod 360 throughthe holes or slots in the screw heads 245, through and beneath varioustissues of the patient, with the rod inserter 245, and, therefore, therod 360, fixed to the inserter 245, being tracked in the surgicalnavigation system. The operator can also use the computer 114 todetermine the required bending angles of the rod 360. For greatervisualization, the geometry of the screws 250 could be loaded into thecomputer 114 and when the position and orientation of the head 255 isgiven to the computer 114 via the probe 280, the computer 114 couldplace this geometry onto the image data and three-dimensional model. Therod 360 geometry could also be loaded into the computer 114 and could bevisible and shown in real time on monitor 106 as the operator is placingit in the screw heads 255.

In an alternative procedure, one or more plates and/or one or more wiresmay be inserted instead of one or more rods 360.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present teachings and inconstruction of this surgical navigation system without departing fromthe scope or spirit of the teachings. Other embodiments of the teachingswill be apparent to those skilled in the art from consideration of thespecification and practice of the teachings disclosed herein. It isintended that the specification and examples be considered as exemplaryonly.

1. A method of positioning an implant in an anatomy, including a firstimplant portion and a second implant portion with a surgical navigationsystem, comprising: positioning the first implant portion through anopening in a soft tissue of the anatomy; tracking a position of thefirst implant portion; interconnecting an implant inserter with thesecond implant portion; determining a location of the second implantportion; and moving the second implant portion relative to the firstimplant portion via determining a location of the second implantportion.
 2. The method of claim 1, wherein positioning a first implantportion through an opening in a soft tissue, moving the second implantportion relative to the first implant portion, or combinations thereofincludes positioning the first implant portion, the second implantportion, or combinations thereof percutaneously.
 3. The method of claim2, wherein tracking a position of the first implant portion includes;interconnecting a tracking apparatus with the first implant portion; andtracking the tracking apparatus interconnected to the first implantportion.
 4. The method of claim 3, further comprising: determining aposition of the portion of the first implant portion; wherein moving thesecond implant portion relative to the first implant portion includesdetermining a location of a second implant portion relative to the firstimplant portion.
 5. The method of claim 4, further comprising:displaying the determined position of the first implant portion and theposition of the second implant portion.
 6. The method of claim 1,further comprising: configuring the second implant portion based upon atracked position of the first implant portion, a determined location ofthe second implant portion, or combinations thereof.
 7. The method ofclaim 1, further comprising: interconnecting a reference frame with theanatomy.
 8. The method of claim 7, further comprising: displaying adetermined position of the second implant portion on a display relativeto a registered image of the anatomy.
 9. The method of claim 1, furthercomprising: interconnecting a tracking apparatus with the implantinserter; and tracking the tracking apparatus.
 10. The method of claim1, wherein determining a location of the second implant further includestracking the tracking apparatus.
 11. The method of claim 9, wherein thetracking apparatus includes a sensor.
 12. The method of claim 11,further comprising: selecting a sensor to include at least one of alight emitter, an infrared light emitter, an electromagnet, a magnet, aradiation emitter, or combinations thereof.
 13. The method of claim 1,further comprising: imaging the anatomy while at least one of trackingthe position of the first implant, tracking the tracking apparatus,determining a location of a portion of the second implant portion, orcombinations thereof.
 14. The method of claim 13, wherein imaging theanatomy includes imaging the anatomy with an ultrasound system.
 15. Themethod of claim 1, further comprising: positioning a third implantportion through an opening in a soft tissue; and interconnecting thefirst implant portion and the third implant portion with the secondimplant portion by moving the second implant portion relative to thefirst implant portion and the third implant portion.
 16. The method ofclaim 1, wherein said first implant portion is a slot in a screw head;wherein said second implant portion is a rod; wherein moving the secondimplant portion includes aligning the rod with the slot.
 17. The methodof claim 16, further comprising: fixing the first implant portion to avertebrae.
 18. The method of claim 1, wherein tracking a positionincludes tracking with an acoustic tracking system, optical trackingsystem, electromagnetic tracking system, micropulsed radar, orcombinations thereof.
 19. A method of performing a spinal procedure inan anatomy with a surgical navigation system, comprising: positioning afirst screw implant in a vertebrae percutaneously through an opening ina soft tissue of the anatomy; tracking a position of the first screwimplant; orientating the first screw implant in a selected orientationat least in part via tracking the position of the first screw implant;interconnecting an implant inserter with a rod; determining a positionof a portion of the rod; and moving the rod relative to the first screwimplant via determining a location of the rod to interconnect the screwwith rod.
 20. The method of claim 19, further comprising:interconnecting a second tracking apparatus with the implant inserter.21. The method of claim 19, wherein orientating said first screw implantincludes orientating a slot defined by the screw.
 22. The method ofclaim 21, wherein tracking a position of the first screw implantincludes interconnecting a screw tracking apparatus with the first screwimplant.
 23. The method of claim 22, wherein interconnecting the screwtracking apparatus includes selecting a sensor.
 24. The method of claim23, wherein selecting the sensor includes selecting a light emittingdiode, a light reflector, an infrared emitter, a magnet, anelectromagnet, an acoustic emitter, an infrared reflector, orcombinations thereof.
 25. The method of claim 22, whereininterconnecting the screw tracking apparatus with the first screwimplant includes positioning the screw tracking apparatuspercutaneously.
 26. The method of claim 22, wherein tracking thetracking apparatus includes at least triangulating a position of thetracking apparatus with the surgical navigational system.
 27. The methodof claim 26, wherein the surgical navigation system includes an acoustictracking system, or electromagnetic tracking system, an optical trackingsystem, a micropulsed radar, or combinations thereof.
 28. The method ofclaim 19, wherein orientating the first screw implant includes selectingan orientation of a head of the screw relative to a portion of theanatomy.
 29. The method of claim 21, wherein orientating the first screwimplant includes orientating the slot relative to the anatomy.
 30. Themethod of claim 29, further comprising: positioning a second screwimplant in a vertebrae percutaneously; and orientating the second screwimplant; wherein orientating the second screw implant includesorientating second screw implant relative to the first screw implant.31. The method of claim 30, wherein moving the rod relative to the firstscrew implant includes moving the rod relative to both the first screwimplant and the second screw implant.
 32. The method of claim 31,further comprising: manipulating the rod to achieve an interconnectionof the first screw implant and the second screw implant.
 33. The methodof claim 19, wherein interconnecting the implant inserter with the rodincludes interconnecting the implant inserter near a first end of therod, a second end of the rod, a portion intermediate between the firstend and the second end, or combinations thereof.
 34. The method of claim19, wherein interconnecting an implant inserter with a rod includesrigidly interconnecting an implant inserter with the rod.
 35. The methodof claim 34, further comprising: interconnecting a tracking apparatuswith the implant inserter that includes rigidly interconnecting thetracking apparatus with the implant inserter.
 36. The method of claim19, wherein interconnecting an implant inserter with a rod includesreleasably interconnecting the implant inserter with the rod.
 37. Themethod of claim 19, further comprising: interconnecting a trackingapparatus with the implant inserter that includes positioning an emitteron the tracking apparatus.
 38. The method of claim 37, whereininterconnecting a sensor with the tracking apparatus includes selectingat least one of a light emitting a diode, a light reflecting portion, aninfrared light emitting portion, an infrared light reflecting portion,an acoustic emitter, an electromagnet, a magnet, or combinationsthereof.
 39. The method of claim 19, further comprising: imaging aportion of the anatomy.
 40. The method of claim 39, wherein imaging aportion of the anatomy includes obtaining an MRI scan, a CT scan, anx-ray image, an ultrasound image, or combinations thereof.
 41. Themethod of claim 19, further comprising: displaying an image of theanatomy; and displaying a position of the portion of the screw on thedisplay relative to the image of the anatomy, and displaying adetermined position of the rod relative to the image of the anatomy. 42.The method of claim 41, wherein moving the rod relative to the screwincludes displaying on the display the portion of the rod relative tothe position of the head of the screw.
 43. The method of claim 42,further comprising: manipulating the rod to achieve a selectedinterconnection of the rod and the screw implant.
 44. The method ofclaim 43, wherein manipulating the rod includes bending the rod.
 45. Themethod of claim 44, further comprising: positioning a second screwimplant in a vertebrae percutaneously; and moving the rod relative tothe screw implant and the second screw implant.
 46. The method of claim19, wherein moving the rod relative to the screw includes moving the rodsubstantially percutaneously.
 47. The method of claim 46, wherein movingthe rod substantially percutaneously includes inserting the rod througha substantially single opening in a soft tissue of the anatomy andmoving the rod based upon a tracked position of the rod.
 48. The methodof claim 47, wherein tracking a position of the portion of the screw anddetermining a position of a portion of the rod is substantiallypercutaneous.
 49. The method of claim 19, wherein tracking the positionof the first screw implant includes tracking a position of a slotdefined by the screw.
 50. The method of claim 49, wherein moving the rodrelative to the first screw implant includes moving the rodpercutaneously through the slot.
 51. The method of claim 50, furthercomprising: positioning a second screw implant in a vertebraepercutaneously through an opening in a soft tissue of the anatomy;tracking a position of the second screw implant; and orientating thesecond screw implant in a selected orientation at least in part viatracking the position of the second screw implant.
 52. The method ofclaim 51, wherein orientating the second screw implant includes aligninga second slot defined by the second screw implant with a first slotdefined by the first screw implant at least in part by tracking theposition of the first screw implant, tracking the position of the firstscrew implant, or combinations thereof; wherein moving the rod includesmoving the rod through the first slot and the second slot;
 53. Themethod of claim 52, further comprising: fixing the rod to the firstscrew implant and the second screw implant.